syms h
A=[0 2 3 3; 0 -2 h 3; 0 0 0 14; 0 0 0 -2];
A(1,:)=A(1,:)/A(1,2);
A(2,:)=A(2,:)-A(2,2)/A(1,2)*A(1,:);
A(3,:)=A(3,:)/A(3,4);
A(4,:)=A(4,:)-A(4,4)/A(3,4)*A(3,:);
A(2,:)=A(2,:)-A(2,4)/A(3,4)*A(3,:);
A(1,:)=A(1,:)-A(1,4)/A(3,4)*A(3,:);
A